Melt butter in large saucepan on medium heat.,Add onions; cook 10 min.,or until golden brown, stirring frequently.,Add broth and steak sauce; stir.,Bring to boil.,______,Preheat broiler.,Ladle soup evenly into 32 ovenproof serving bowls (or 4 bowls for trial recipe).,Top each with 1 bread slice and 1/4 cup of the cheese.,Broil 2 to 3 min.,or until cheese is melted.